blocks|key|450452|text|如果你得到一个“未定义的方法”错误，那就意味着这个方法在被调用的时候是不可访问的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|450453|如果您试图从帮助器调用该方法，则需要将该方法放在您的ApplicationHelper中，而不是ApplicationController中。如果您还想从您的控制器访问它，请在您的ApplicationController中输入以下内容：|450454|helper_method+:date_to_day_of_week|code-block|syntax|javascript|450455|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

If you're getting an "undefined method" error, that means this method is inaccessible from the point it's being called. 

If you're trying to call it from a helper, you need to place the method in your ApplicationHelper, not your ApplicationController. If you also want it to be accessible from your controllers, then put the following in your ApplicationController:

<pre><code>helper_method :date_to_day_of_week
</code></pre>

blocks|key|5603944|text|假设dt+=+Time.now()+dt.strftime("%25a")为您提供日期|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5603945|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

say dt = Time.now()
dt.strftime("%a")
gives you the day

blocks|key|453319|text|尝尝这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|453320|def+date_to_day_of_week(date)
++Date.parse(date).strftime("%25a").downcase
end|code-block|syntax|javascript|453321|Ruby返回方法中计算的最后一个值，因此您不需要专门返回任何内容。另外，还有！小写！简单地更改被调用的字符串的值，而不是像您期望的那样返回值。|453322|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

try this

<pre><code>def date_to_day_of_week(date)
 Date.parse(date).strftime("%a").downcase
end
</code></pre>

Ruby returns the last value evaluated in a method, so you do not need to specifically return anything. Also, the ! in downcase! simply changes the value of the string it was called on rather than returning the value as you're expecting.

blocks|key|453288|text|看看ActiveSupport::CoreExtensions::Date::Conversions.您可以定义自己的DATE_FORMATS并使用"to_formatted_s“将其输出。我相信你想要的缩写月份是"%25b“|type|unstyled|depth|inlineStyleRanges|entityRanges|data|453289|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Look at ActiveSupport::CoreExtensions::Date::Conversions. You can define your own DATE_FORMATS and output it with "to_formatted_s". I believe what you want for an abbreviated month is "%b"

blocks|key|3492090|text|这段代码在哪里？例如，如果它在一个由控制器调用的模型中，你可能想要使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3492091|def+self.date_to_day_of_week(date)
++d+=+Date.parse(date).strftime("%25a").downcase!
++return+d
end|code-block|syntax|javascript|3492092|并使用以下命令在控制器中调用它：|3492093|def+index
++#+...
++@date+=+Model.date_to_day_of_week("2009-12-30")
end|3492094|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Where is this code located? If, for instance, it's in a model called by a controller you may want to go with:

<pre><code>def self.date_to_day_of_week(date)
 d = Date.parse(date).strftime("%a").downcase!
 return d
end
</code></pre>

And call it in your controller with:

<pre><code>def index
 # ...
 @date = Model.date_to_day_of_week("2009-12-30")
end
</code></pre>

blocks|key|2360144|text|你试过了吗|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2360145|日期=+Date.parse(date).strftime("%25a").to_s.downcase|offset|length|style|BOLD|2360146|由于ActiveSupport的原因，rails和ruby中的date方法的工作方式略有不同|2360147|entityMap^0|0|10|4|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|P|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|K|$]]

Did you try 

day = Date.parse(date).strftime("%a").to_s.downcase

The date methods do work slightly differently within rails versus ruby, because of ActiveSupport

I have a date string: "2009-10-12". I would like to write a method that takes this as a parameter and returns the three lettered day of the week (in this case 'mon'). I wrote this:

<pre><code>def date_to_day_of_week(date)
 d = Date.parse(date).strftime("%a").downcase!
 return d
end
</code></pre>

When I call this from script/console, it works as expected. However, when I call this from within my app I get a variety of different errors depending on what I do. The main problems are that either <code>date_to_day_of_week</code> is an undefined method, or if I move the contents of the method (i.e. <code>day = Date.parse(date).strftime("%a").downcase!</code> inline, then I get <code>private method gsub! called for Mon, 12 Oct 2009:Date</code>. I just think I'm starting to understand Ruby and Rails and then I get thrown back to the start!

Can anyone help with this?

Gav

Converting a date string

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个日期字符串："2009-10-12“。我想写一个方法，它将this作为参数，并返回一周中三个字母的日期(在本例中为'mon')。我写了以下内容：def date_to_day_of_week(date)  d = Date.parse(date).strftime("%a").downcase!  return...

问转换日期字符串
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